diversity Communication The Young Stages of the Cannonball Jellyfish (Stomolophus sp. 2) from the Central Gulf of California (Mexico) Laura Cristina Gómez-Salinas 1 , Juana López-Martínez 2,* and André Carrara Morandini 3,4 1 Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, Mexico; [email protected] 2 Centro de Investigaciones Biológicas del Noroeste S.C (CIBNOR), Guaymas 85460, Mexico 3 Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 101 trav. 14, São Paulo 05508-090, SP, Brazil; [email protected] 4 Centro de Biologia Marinha, Universidade de São Paulo, Rodovia Dr Manoel Hipólito do Rego km 131.5, São Sebastião 11612-109, SP, Brazil * Correspondence: [email protected] Abstract: Exploitation of the cannonball jellyfish (Stomolophus sp. 2) is increasing in Mexico and USA due to successful fisheries associated with seasonal blooms in coastal areas. Previously, it was proposed that such blooms could be identified by recognizing the presence of young stages in the water. In our work, we aim to describe the young stages (ephyra and metaephyra) found in the Las Guásimas lagoon, Sonora, Mexico. The description of specimens is based on photographs, drawings, and morphological measurements aimed at helping in the early detection of blooming events. Keywords: ephyrae; development; edible jellyfish; rhizostome Citation: Gómez-Salinas, L.C.; López-Martínez, J.; Morandini, A.C. The Young Stages of the Cannonball Jellyfish (Stomolophus sp. 2) from the Central Gulf of California (Mexico). 1. Introduction Diversity 2021, 13, 229. https:// In Western countries, jellyfish are usually associated with bad memories, mostly doi.org/10.3390/d13060229 due to the stings these marine animals can inflict on humans [1–4]; however, in Eastern countries, jellyfish are synonymous with a fine dish or delicacy [5–8], and eventually Academic Editors: Michael Wink, have been associated with many medicinal properties [9]. The use of jellyfish as food Alenka Malej and Agustín Schiariti has long been recognized in many places. It is only recently that Western countries have recognized its importance as an economic product [10–12]. In many places, jellyfish fisheries Received: 27 April 2021 have been developed, and then declined [13], due to different factors (e.g., fluctuation of Accepted: 10 May 2021 stocks or lower interest of fishery companies), but some countries are fortunate to have Published: 24 May 2021 certain valuable species in their territorial waters. Among the most valued features are the thickness and weight of the gelatinous part [5,9,11]. The rhizostome genus Stomolophus L. Publisher’s Note: MDPI stays neutral Agassiz, 1860 morphologically embraces such features and is widely distributed on both with regard to jurisdictional claims in sides of the American continents [14,15]. published maps and institutional affil- Historically, five species of Stomolophus have been described (S. agaricus, S. chunii, iations. S. collaris, S. fritillaria, and S. meleagris) [15–18]. However, most records have mention only S. meleagris, with some of those possibly based on misidentifications [16,19,20]. Scypho- zoan systematics currently considers only two of the species to be valid (S. meleagris and S. fritillarius), both from the Atlantic Ocean [15,21]. A recent study [22] revealed cryptic Copyright: © 2021 by the authors. diversity within this jellyfish genus, hypothesizing five undescribed species from the Pacific Licensee MDPI, Basel, Switzerland. Ocean. As mentioned by Gómez-Daglio and Dawson [22] and Getino-Mamet et al. [23], This article is an open access article the existence of different species within the genus Stomolophus is an ongoing investigation distributed under the terms and that is not yet entirely conclusive, nor has it reached a broad scientific consensus. Although conditions of the Creative Commons Gómez-Daglio and Dawson [22] proposed the existence of different species, the holotypes Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ mentioned in their research have not yet been described; in addition, the distribution 4.0/). Diversity 2021, 13, 229. https://doi.org/10.3390/d13060229 https://www.mdpi.com/journal/diversity Diversity 2021, 13, x FOR PEER REVIEW 2 of 8 Diversity 2021, 13, 229 2 of 8 distribution frequency of significant genetic distances that the authors reported only de- frequency of significant genetic distances that the authors reported only detected two tected two discontinuities [24]. discontinuities [24]. Jellyfish of the genus Stomolophus are commercially exploited by many different Jellyfish of the genus Stomolophus are commercially exploited by many different countries in the Americas [11]. In Mexico, especially in the Sonora region, there are favor- countries in the Americas [11]. In Mexico, especially in the Sonora region, there are able conditions for conducting jellyfish fisheries. Species in the area present marked sea- favorable conditions for conducting jellyfish fisheries. Species in the area present marked sonalityseasonality (winter (winter and andspring) spring) and andcan canonly only be exploited be exploited during during a few a few months months [10]. [10 Litt]. Littlele is knownis known about about the thepolyp, polyp, planula planula,, and and ephyra ephyra stage stagess of ofthe the jellyfish jellyfish S.S. meleagris meleagris. .D Despiteespite theirtheir commercial commercial importance, importance, much much less less is is known known about about their their distribution distribution and and settlement settlement areas,areas, which which is is information information that that is is more more than than desirable desirable for for management management pu purposes,rposes, as as they they areare a areservoir reservoir for for subsequent subsequent outbreaks outbreaks,, although although this this is is still still difficult difficult to to prove prove [25,26 [25,26]].. TheThe identification identification of of the the early early stage stage (ephyrae) (ephyrae) can can provide provide evidence evidence for for forecast forecastinging jellyfishjellyfish blooms blooms [27,28 [27,28], which], which is importance is importance for foreffective effective management management of all of aspects all aspects of the of fishery.the fishery. PreviousPrevious studies studies have have described described the the ephyra ephyra stage stage of of S.S. meleagris meleagris ofof some some Atlantic Atlantic pop- pop- ulationsulations [16,29,30] [16,29,30,], however, however, for for the the Pacific Pacific region region,, there there is is only only a aPanamanian Panamanian study study [31 [31]. ]. AlthoughAlthough the the species species ha haveve been been mentioned mentioned in inseveral several studies studies in the in theGulf Gulf of California of Califor- [24,nia32 [24–36,32], –little36], littleis known is known about about how howto recognize to recognize and identify and identify the young the young medusae. medusae. TheThe goals goals of ofthis this work work were were to identify to identify the young the young stage stage(ephyrae) (ephyrae) found in found Las Guás- in Las imasGuá Bsimasay and Bay to describe and to describe the differ theent different developmental developmental stages of stagesthe ephyrae. of the We ephyrae. highlight We thathighlight, in the that,study in area, thestudy the only area, adult the onlyjellyfish adult species jellyfish found species is Stomolophus found is Stomolophus sp. 2, whichsp. is 2, heavilywhich isfished heavily during fished the during season. the season. 2.2. Materials Materials and and Methods Methods ◦ 0 TheThe study study was was conducted conducted in in Las Las Guásimas Guásimas lagoon, lagoon, Sonora, Sonora, Mexico Mexico (Figure (Figure 11)) (27°49 (27 49’– – 0 ◦ 0 0 2 5555’ NN 110°29 110 29’–45–45’ W).W). The The lagoon lagoon has has an an area area of of 51 51 km km2, with, with an an opening opening of of 2 2km km to to the the GulfGulf of of California. California. There There is is seasonal variation inin temperaturestemperatures (winter/summer) (winter/summer) from from 17 17 to ◦ to34 34 C,°C , with with a a salinity salinity of of 36 36 to to 41 41 ups. ups. Figure 1. Figure 1. CollectingCollecting area, area, Las Las Guásimas Guásimas lagoon, lagoon, Sonora, Sonora, Mexico, Mexico, and and central central Gulf Gulf of of California. California. We performed superficial zooplankton tows (250 microns) every month from 2014 We performed superficial zooplankton tows (250 microns) every month from 2014 to to 2016, inside and outside the lagoon. The samples were preserved in 4% formaldehyde 2016, inside and outside the lagoon. The samples were preserved in 4% formaldehyde solution (buffered with sodium borate) the samples were inspected and all ephyrae were solution (buffered with sodium borate) the samples were inspected and all ephyrae were sorted. All individuals were measured following Straehler-Pohl and Jarms [27], Straehler- sorted. All individuals were measured following Straehler-Pohl and Jarms [27], Straehler- Pohl et al. [37], and Holst [28] (Figure2). Total body diameter (TBD), central disk diameter Pohl(CDD), et al. total [37], marginal and Holst lappet [28] (Figure length 2 (TMLL),). Total body lappet diameter stem length (TBD), (LStL), central rhopalial disk diameter lappet (CDD),length total (RLL), marginal as well lappet as the bodylength proportions, (TMLL), lappet i.e., CDD/TBDstem length× (LStL),100, RLL/TMLL rhopalial lappet× 100, lengthTMLL/TBD (RLL), ×as100, well and as LStL/TMLLthe body proportions× 100 were, i.e., calculated CDD/TBD (Figure × 100,2). RLL/TMLL × 100, TMLL/TBD × 100, and LStL/TMLL × 100 were calculated (Figure 2). Diversity 2021, 13, x FOR PEER REVIEW 3 of 8 Diversity 2021, 13, 229 3 of 8 FigureFigure 2. Ephyrae 2. Ephyra of Stomolophuse of Stomolophussp. 2, and measurements sp. 2, and taken measurements following Straehler-Pohl taken and following Straehler-Pohl and Jarms [27] and Straehler-Pohl et al. [37]. Jarms [27] and Straehler-Pohl et al. [37]. We also observed the shape of the “rhopalial lappet”, “rhopalial canal”, and “velar canal” of every specimen to record the differences in each stage.